In the field of internal combustion engines, it is known to allow cooling in a coolant circuit to separately flow through the engine block and cylinder head of the internal combustion engine. The cylinder head, which is thermally coupled to the combustion gas especially through the combustion chamber and duct walls, and the engine block, which is thermally coupled especially to the friction points, can thereby be cooled differently. Systems which allow the cylinder head and block to be separately cooled are referred to as “split-cooling systems”. In such systems, in the hot-running phase of the internal combustion engine, the cylinder head may be cooled upstream of the engine block, as a result of which the engine block can be brought up to a desired operating temperature more rapidly.
For example, EP 2 309 106 A1 describes an internal combustion engine which has a coolant circuit which is divided into a cylinder-block-side coolant region and into a cylinder-head-side coolant region. The cylinder-block-side coolant region has at least one block thermostat. The cylinder-head-side coolant region has an outlet-side cooling region and an inlet-side cooling region, wherein coolant can be conducted from the inlet-side cooling region into an outlet housing, into which the outlet-side cooling region leads. A coolant pump outlet is connected to the cylinder-block-side coolant region via the block thermostat. Arranged upstream of the block thermostat is at least one branch which conducts a first partial flow in the direction of the outlet-side cooling region of the cylinder-head-side coolant region, wherein the at least one branch is directly connected to the coolant pump outlet. The coolant flowing through the block thermostat flows through the cylinder-block-side coolant region and from there enters the inlet-side cooling region of the cylinder-head-side coolant region. The cylinder-block-side coolant region is connected to the inlet-side cooling region through a cylinder head seal. The outlet housing has a control element. The coolant flowing out of the outlet-side and inlet-side cooling region are mixed in the direction of flow upstream of the control element in the outlet housing. The two coolant flows entering the outlet housing are free of contact until they are mixed.
However, the inventor has recognized several drawbacks with EP 2 309 106 A1 and other previous cylinder block cooling systems. For instance, the cooling conduits in the cylinder block may compromise the structural integrity of the cylinder block. As a result, the durability and longevity of the cylinder block may be decreased.
To address at least some of the aforementioned problems a cooling system is provided. In one example, the cooling system includes a cylinder bore including a central axis, a coolant duct including a first section positioned on a first side of the cylinder bore and a second section positioned on a second side of the cylinder bore, a connecting duct extending between the first section and the second section and including a first end opening into the first section and a second end opening into the second section. The connecting duct includes a first subsection and a second subsection extending inwardly toward the central axis and an intersection of the first subsection and the second subsection in a plane perpendicular to the central axis form a non-straight angle. Arranging the first and second subsections of the connecting duct at a non-straight angle enables the structural integrity of the cylinder block to be increased while providing a desired amount of cooling to the cylinder block. In this way, increased cylinder block cooling may be achieve without compromising the structural integrity of the block, if desired. As a result, engine efficiency can be increased, engine emissions can be reduced, and engine longevity can be increased, if desired.
It should be understood that the summary above is provided to introduce in simplified form a selection of concepts that are further described in the detailed description. It is not meant to identify key or essential features of the claimed subject matter, the scope of which is defined uniquely by the claims that follow the detailed description. Furthermore, the claimed subject matter is not limited to implementations that solve any disadvantages noted above or in any part of this disclosure.